Recent model consensus from sources like the GFS and regional forecasts points to a cold front and associated rainfall arriving over São Paulo on September 22, driving overnight lows toward 15–18 °C under persistent cloud cover and northerly-to-southerly wind shifts. This setup favors the 14 °C-or-below outcome near 46.5 % market-implied odds, as enhanced mixing and precipitation suppress radiational cooling yet still allow temperatures to dip below seasonal norms. Conversely, any delay in frontal passage or stronger warm advection could sustain minimums near or above 20 °C, supporting the closely matched 24 °C-or-higher probability at 43.5 %. Key upcoming inputs include the next NHC/INMET model runs and surface observations confirming whether the low falls inside or outside the 15–19 °C cluster where secondary probabilities cluster around 19–25 %.